1. Field of the Invention
This invention relates generally to game boards or cards used in playing the game of bingo.
2. Prior Art
In known reusable bingo cards of the type commonly used by commercial bingo parlors, a paper number sheet having the rectangular array of 24 numbers and the central "free" space is sandwiched between top and bottom cardboard sheets. The margins of the cardboard sheets are sewn together with string or heavy thread.
The numbers printed on the paper sheet are viewed through windows in the top sheet. When desired, any of the numbers can be covered by a separate, substantially transparent, red plastic slide by manipulation of a short upstanding leg extending out from the main body of the slide. Such leg projects through a transverse slot in the top sheet generally below the window for the number to be covered.
As evidenced by the newspaper article titled "Officers got their number; 3 bingo cheats collared" by Dee Norton, appearing in the Oct. 30, 1982 edition of The Seattle Times on page A-7, bingo games with valuable prizes have attracted cheaters who steal bingo cards, alter them and then return to the game hall or parlor to use the altered cards. As indicated in the article, substantial sums have been paid out to cheaters using such altered bingo cards. In the system described in the newspaper article, a stolen card is sliced open along an edge and a small paper disc having several printed numbers is inserted between the top sheet and number sheet so that any of the several numbers on the disc can be made to appear in one of the windows. The altered cards are then restitched so that they appear identical to the original cards.
The problem of cheating by altering the reusable cards has led to the use of throwaway, manually marked paper bingo sheets, at least for the games having the most valuable prizes.